Welcome! I'd recommend this article for you: www.sparkpeople.com/resource/motivation_ar
And I understand you feel disappointed, but try to look on the bright side. You are doing a good thing for yourself now. The only way you could make things worse is doing nothing, so you deserve some respect for getting back on the horse!
Just remember there is more to losing weight than nutrition and exercise. It has to become your new lifestyle, something you enjoy and can continue doing the rest of your life. Not something stressful and restrictive like most "diets" are.
Do your best! And look into the article here at SparkPeople about motivation and wellness. They're a gold mine.